Chemical synthesis (see below) is an essential part of the modern world. But traditional methods are becoming increasingly unacceptable because:
- the processes are hazardous (explosion, toxicity)
- they consume scarce resources (metals, petrochemicals, etc.)
- the by-products (unwanted materials, which are often discharged to the environment) are hazardous (toxic, etc.)
- they are energy-intensive
This page tells you something about the background science. Don't be afraid - you'll know most of it already.
The chemical industry is one of the largest manufacturing sectors worldwide and every household and industry uses thousands of goods which depend on chemical synthesis.:
Polymers and plastics, especially polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polystyrene and polycarbonate comprise about 80% of the industry’s output worldwide. Chemicals are used to make a wide variety of consumer goods, as well as thousands inputs to agriculture, manufacturing, construction, and service industries. The chemical industry itself consumes 26 percent of its own output. Major industrial customers include rubber and plastic products, textiles, apparel, petroleum refining, pulp and paper, and primary metals. Chemicals is nearly a $3 trillion global enterprise, and the EU and U.S. chemical companies are the world's largest producers.
In chemistry, chemical synthesis is purposeful execution of chemical reactions to get a product, or several products. This happens by physical and chemical manipulations usually involving one or more reactions. In modern laboratory usage, this tends to imply that the process is reproducible, reliable, and established to work in multiple laboratories.
A chemical synthesis begins by selection of compounds that are known as reagents or reactants. Various reaction types can be applied to these to synthesize the product, or an intermediate product. This requires mixing the compounds in a reaction vessel such as a chemical reactor or a simple round-bottom flask. Many reactions require some form of work-up procedure before the final product is isolated. The amount of product in a chemical synthesis is the reaction yield. Typically, chemical yields are expressed as a weight in grams or as a percentage of the total theoretical quantity of product that could be produced. A side reaction is an unwanted chemical reaction taking place that diminishes the yield of the desired product.
The substance/substances initially involved in a chemical reaction are called reactants. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Different chemical reactions are used in combination in chemical synthesis in order to get a desired product.
The problem is that chemical synthesis is not easy! Creating complex materials from simpler ones usually requires energy and a very careful choice of reagents.
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction …".
//Although the terms reactant and reagent are often used interchangeably, a reactant is more specifically a "substance that is consumed in the course of a chemical reaction". Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants. In organic chemistry, reagents are compounds or mixtures, usually composed of inorganic or small organic molecules, that are used to affect a transformation on an organic substrate. //
There are millions of chemical reactions reported every year. All chemists are aware of the need to develop greener processes. We'll try to help measure how effective this is.